.choose-1 {
    width: 600px;
    height: 350px;
    background-color: #F5F5F5;
    border-radius: 4px;
    position: relative;
    background-image: linear-gradient(to bottom, #ECEFF1, #B0BEC5);
    background-repeat: no-repeat;
    background-size: cover;
    background-position: center center;
    display: flex;
    /* justify-content: center; */
    /* align-items: center; */
    flex-direction: column;
    background: url(../img/choose-1/choose.jpg) no-repeat center center/100% 100%;
}

.choose-1 .content1 {
    height: 40px;
}

.choose-1 .content2 {
    width: 600px;
    height: 329px;
    /* background-color: white; */
    border-radius: 4px;
    position: relative;
    background-repeat: no-repeat;
    background-size: cover;
    background-position: center center;
    text-align: center;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
}

.choose-1 .difficulty {
    height: 60px;
    width: 150px;
    /* margin-top: 120px; */
    background: url(../img/choose-1/choose_dif.png) no-repeat center center/100% 100%;
    border: none;
}

.choose-1 .difficulty:hover {
    height: 60px;
    width: 160px;
}

.choose-1 .introduction {
    height: 60px;
    width: 150px;
    margin-top: 10px;
    background: url(../img/choose-1/game_introduction.png) no-repeat center center/100% 100%;
    border: none;
}

.choose-1 .introduction:hover {
    height: 60px;
    width: 160px;
}